It is planned to limit the deleterious consequences of retinal dystrophy in RCS rats in transgenic rats with human rhodopsin mutation by introducing cells to the subretinal space. There are five specific aims. 1) To study efficacy of alternatives to fresh RPE cells in preventing photoreceptor degeneration resulting from a defect in the photoreceptors themselves or in the adjacent RPE. Immortalized human RPE cell lines and Schwann cells will be used as donor cells, transplanting them either to RCS rats or to transgenic rats with mutations in the rhodopsin gene causing a moderate rate of degeneration. 2) To examine how grafted cells settle in the subretinal space, how they interrelate with adjacent cells and how long they survive. 3) To examine how numbers and distribution of grafted cells correspond with the degree of photoreceptor rescue. 4) To examine how photoreceptor rescue correlates with spared central visual function. 5) To use grafted cells as vectors for introduced molecules. The purpose of the work is twofold. First, it will provide essential background data necessary in assessing the feasibility of developing a transplantation approach for patients with retinal degenerative diseases such as retinitis pigmentosa and age related macular degeneration. Second, it will also approach the basic biology of degeneration and repair, which in itself will provide insights into factors that may influence photoreceptor survival and perhaps obviate the need for transplantation as a potential therapy.